1. Field
This disclosure relates generally to semiconductor devices, and more specifically, to vias on a bridge connecting two buses.
2. Related Art
Semiconductor devices often have parallel lines that are connected by a bridge. The lines are often considered buses because they are relatively wide for low resistance so as to be able to carry relatively high currents without causing problematic voltage drop. For a given technology, the depth of the lines at a given metal level is the same so that width is the variable in determining resistance per unit of length. Increasing width reduces resistance, but requires more area as well as increasing the risk of voiding at the vias. The stress can result in a variety of failures including via failure. Although via failures may have a low probability of occurring, there are often millions of vias on a given semiconductor device. The result is that a likelihood of at least one via failure is relatively high. Thus, it has become common to provide redundant vias with the view that it is unlikely that two vias will fail at the same location. This has been effective, but as geometries continue to shrink, via failures, even at redundant via locations, continue to occur.
Accordingly, there is a need for further improvement in reducing via failures.